1. Field of the Invention
The present invention relates to a semiconductor vapor phase growth apparatus and, more particularly, to an apparatus for automatically vapor phase-growing a semiconductor substrate while continuously conveying the substrate and controlling a process in the vapor phase growth according to a predetermined process program.
2. Discussion of the Background
A vapor phase growth apparatus for vapor phase-growing a semiconductor on a wafer has become widely used as semiconductor chips have recently come to be used in a wide variety of industrial fields.
Conventional vapor phase growth apparatuses can be broadly categorized as either a batch type processing system or a continuous type processing system. The former system generally has a structure wherein a rotatable susceptor on which to place wafers is provided in a cylindrical reaction furnace, a heater is mounted below the susceptor, and gas necessary for vapor phase growth is supplied to the interior. The inventors have devised an automatic controller for such a batch type processing system (as disclosed in U.S. Pat. No. 4,430,959) which is able to perform a complicated process with good reproducibility. However, this batch type system had to open and close the furnace door every time wafers are conveyed into or out of the furnace. Thus, since the wafers had to be conveyed into and out of the furnace at every batch, this type of processing system has the drawback in that its processing efficiency is very low.
The latter, i.e. continuous processing type system is superior to the former system in that a wafer is vapor phase-grown while it is being continuously conveyed. However, the operating process of the batch type system differs completely from that of the continuous type system. The continuous type system has heretofore been operated by setting the conveying speed of the wafer and a gas flow rate by means of potentiometers, and manually controlling the temperatures by means of a commercially available thermometer. Thus, the operating steps of the continuous type system are very complicated and deteriorated in its reproducibility and reliability.